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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

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the crevasses being short and extending in various directions, giving the glacier the appearance characteristic of an ice fall. Its pinnacled condition was only in small part due to greater ablation, for even here a large part of the surface was still protected by moraine. The glacier surface had the appearance of having been broken by dragging and shoving as the strain of the glacier flood swept down the deeper central portion and caused a swelling of the ice against the valley margins, the thinner marginal portion having too great rigidity to accommodate itself to the strains thus induced. One was reminded somewhat of the broken blocks of ice that are piled up along the margin of a frozen river that rises in flood. This condition extended all along the visible margin and was strikingly developed both on the stoss slope of the nunatak and around its eastern base.
Above Terrace Point the glacier was also badly crevassed. Those tributaries that enter from the west were not notably broken, but two that enter from the east, just above Terrace Point, were impassably crevassed where they emerged from their valleys, and the crevassing of these extended for only a half mile into the main glacier. It seems certain that some of the impulse of the advance of Lucia Glacier was supplied by these tributaries, but the greater part was apparently supplied from the main glacier, which was badly crevassed above these two tributaries, and, in fact, as far into the mountains as we could see. A noteworthy feature of the glacier above Terrace Point was the presence of a crescentic depression between the crevassed area of the two eastern tributaries and the crevassed main glacier. It is as if the glacier level were raised by the impulse from the main glacier, while the advance of the two tributaries had raised a crevassed